CHM 130 Lisa Diebolt Spring ’07 Quiz 4. TAKE HOME. KEY

A. Completing and Balancing Reactions

1. Refer to the activity series for the single replacement reactions & write NR if the reaction will not occur. Complete and balance the reactions that do occur. (7 pt)

a) 2 Au(NO₃)₃ (aq) + 3 Mg (s) ® 3 Mg(NO₃)₂ (aq) + 2 Au (s)

b) __ NaCl (aq) + __ Al (s) ® NR

c) __ PbCl₂ (aq) + 2 Na (s) ® 2 NaCl (aq) + Pb (s)

2. Complete and balance the following acid base neutralization and combustion reactions. (6 pts)

a) __ C₄H₁₀O (l) + 6 O₂ (g) ® 5 H₂O (g) + 4 CO₂ (g)

b) __ H₃PO₄ (aq) + 3 NaOH (aq) ® 3 H₂O (l) + Na₃PO₄ (aq)

B. Show work and include units for answers! (Can attach work)

1. What is the molar mass of Co₂(CrO₄)₃? (1 pt)

MM Co₂(CrO₄)₃ = 2(58.93) + 3(52.00) + 12(16.00) = 465.86 g/mol

2. How many moles are there in 21.5 g of (NH₄)₃PO₄? (2 pts)

MM (NH₄)₃PO₄ = 3(14.01) +12(1.01) + 30.97 + 4(16.00) = 149.12 g/mol

0.144 mol (NH₄)₃PO₄

3. How many grams is 6.65 moles of Mg(C₂H₃O₂)₂? (2 pts)

MM Mg(C₂H₃O₂)₂ = 24.31 + 4(12.01) + 6(1.01) + 4(16.00) = 142.41 g/mol

947 g Mg(C₂H₃O₂)₂

4. What is the mass of 13.5 L of N₂O₄(g) at STP? (3 pts)

55.5 g N₂O₄

5. What is the % composition of Fe₂(SO₄)₃? (4 pts)

MM Fe₂(SO₄)₃ = 2(55.85) + 3(32.07) + 12(16.00) = 399.91 g/mol

27.93 % Fe

24.06 % S

48.01 % O